clapper: Properly export external API symbols

src/lib/shared/clapper-api-visibility.h.in

@@ -0,0 +1,45 @@
+/* Clapper API Visibility
+ * Copyright (C) 2024 Rafał Dzięgiel <rafostar.github@gmail.com>
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 2.1 of the License, or (at your option) any later version.
+ *
+ * This library is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with this library; if not, write to the
+ * Free Software Foundation, Inc., 51 Franklin St, Fifth Floor,
+ * Boston, MA 02110-1301, USA.
+ */
+
+#pragma once
+
+#if !defined(__@CLAPPER_API@_INSIDE__) && !defined(@CLAPPER_API@_COMPILATION)
+#error "This header file can not be included directly."
+#endif
+
+#if (defined(_WIN32) || defined(__CYGWIN__)) && !defined(@CLAPPER_API@_STATIC_COMPILATION)
+#define _@CLAPPER_API@_EXPORT __declspec(dllexport) extern
+#define _@CLAPPER_API@_IMPORT __declspec(dllimport) extern
+#elif __GNUC__ >= 4
+#define _@CLAPPER_API@_EXPORT __attribute__((visibility("default"))) extern
+#define _@CLAPPER_API@_IMPORT extern
+#else
+#define _@CLAPPER_API@_EXPORT extern
+#define _@CLAPPER_API@_IMPORT extern
+#endif
+
+#if defined(@CLAPPER_API@_COMPILATION)
+#define _@CLAPPER_API@_VISIBILITY _@CLAPPER_API@_EXPORT
+#else
+#define _@CLAPPER_API@_VISIBILITY _@CLAPPER_API@_IMPORT
+#endif
+
+#define @CLAPPER_API@_API                _@CLAPPER_API@_VISIBILITY
+#define @CLAPPER_API@_DEPRECATED         G_DEPRECATED _@CLAPPER_API@_VISIBILITY
+#define @CLAPPER_API@_DEPRECATED_FOR(f)  G_DEPRECATED_FOR(f) _@CLAPPER_API@_VISIBILITY